It is known, in watchmaking, to mount parts on arbours by driving in said parts, i.e. via plastic deformation of the part and/or the arbour. The advent of parts made of silicon, makes it impossible to secure said parts by driving them onto arbours because of the risk of breakage thereof. In current fabrication systems, a polymer type adhesive material is used to secure the silicon parts to their arbours or another locking system involving a third mechanical part. However, these solutions are not satisfactory because, in the first solution, the adhesive materials age randomly and sometimes very prematurely and the second solution is too complex to implement.